Liquid discharge head

ABSTRACT

A liquid discharge head includes a recording element substrate including an electrode pad, a support member including a recess that supports the recording element substrate on a bottom surface thereof, an electric wiring member, and a sealant. The electric wiring member includes an opening through which the recording element substrate is exposed, an electric lead wire extending from the opening and connected to the electrode pad, and a protrusion formed in the opening and extending between a side surface of the recording element substrate and an inner side surface of the recess facing the side surface. A distal end of the protrusion is in contact with the bottom surface of the recess. The sealant is disposed in a region surrounded by a surface of the protrusion, the bottom surface of the recess, the inner side surface of the recess, and the side surface of the recording element substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid discharge head that dischargesink toward a recording medium such as recording paper and a method ofmaking the liquid discharge head.

2. Description of the Related Art

A liquid discharge head includes a recording element substrate, aflexible wiring substrate, and a support member. Electrothermaltransducers, ink chambers, and other components are disposed in therecording element substrate. The flexible wiring substrate electricallyconnects the recording element substrate to a recording apparatus body.The support member supports the recording element substrate and theflexible wiring substrate. In general, the recording element substrateand the flexible wiring substrate are affixed to and supported by thesupport member. Electrode lead wires, which extend from the flexiblewiring substrate, are superposed on and joined to electrode pads of therecording element substrate. The electrode lead wires, the electrodepads, and the joints therebetween are sealed with a sealant.

In an existing technology, the front side of the electrode lead wiresand the back side of the electrode lead wires are sealed with differentsealants. To be specific, the recording element substrate is disposed ina recess of the support member, and a gap between an inner surface ofthe recess and a side surface of the recording element substrate isfilled with a first sealant. The first sealant has a comparatively highfluidity and can flow into a small gap on the back side of the electrodelead wires, while the first sealant has elasticity when cured. The backside of the electrode lead wire is sealed with the first sealant havingsuch characteristics. Moreover, a second sealant is applied to the frontside of the electrode lead wires including the joints between theelectrode lead wires are the electrode pads. The second sealant has highadhesion strength and hardness when cured and is capable of maintainingthe shape with which the sealant was applied. The second sealantprotects the electrode lead wires, the electrode pads, and the jointsagainst an external force that is exerted on these portions due towiping or the like. In the description below, the electrode lead wires,the electrode pads, and the joints may be collectively referred to as an“electrical connection portion”.

It is desirable that a sealant is not in contact with the outerperiphery of the recording element substrate excluding the electricalconnection portion. In other words, it is desirable that the sealant beapplied to only a predetermined region of the outer periphery of therecording element substrate. This is because, an unwanted external forcemay act on the recording element substrate when the sealant expands andcontracts due to change in the environment. In particular, if the sizeof the recording element substrate is reduced in order to reduce thesize of the liquid discharge head, it becomes more likely that therecording element substrate become deformed by such an external force,and thereby ink discharge error may occur or the landing accuracy of inkdroplets may decrease.

If a sealant having a high fluidity, such as the aforementioned firstsealant, is used to seal the electrical connection portion, the sealantmay flow out of the predetermined region. On the other hand, if asealant having a high viscosity, such as the aforementioned secondsealant, is used to seal the electrical connection portion, theelectrical connection portion may not be completely covered by thesealant.

U.S. Pat. No. 7,240,991 describes a method of forming a barrier of anadhesive to prevent a sealant having a high fluidity from flowing out ofa predetermined region. To be specific, a barrier is formed between aregion of the outer periphery of a recording element substrate in whichan electrical connection portion is formed and the remaining region soas to separate the region from the remaining region. After forming thebarrier, the sealant is applied.

With the technology described in U.S. Pat. No. 7,240,991, the number ofused materials increases because the barrier is formed from an adhesivethat is different from the sealant. Moreover, because the steps ofapplying the adhesive and curing the adhesive are necessary, the numberof production steps increase and thereby the production cost mayincrease.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a liquid dischargehead includes a recording element substrate including an electrode padfor sending a signal to an element that generates energy used todischarge liquid; a support member including a recess that supports therecording element substrate on a bottom surface thereof; an electricwiring member joined to a surface of the support member in which therecess is formed, the electric wiring member including an openingthrough which the recording element substrate is exposed, an electriclead wire extending from the opening and connected to the electrode pad,and a protrusion formed in the opening and extending between a sidesurface of the recording element substrate and an inner side surface ofthe recess facing the side surface, a distal end of the protrusioncontacting the bottom surface of the recess; and a sealant disposed in aregion surrounded by a surface of the protrusion, the bottom surface ofthe recess, the inner side surface of the recess, and the side surfaceof the recording element substrate.

According to a second aspect of the present invention, a method ofmaking a liquid discharge head includes preparing a recording elementsubstrate, a support member, and an electric wiring member, therecording element substrate including an electrode pad for sending asignal to an element that generates energy used to discharge liquid, thesupport member including a recess for supporting the recording elementsubstrate on a bottom surface thereof, the electric wiring memberincluding an electric lead wire to be connected to the electrode pad andan opening through which the recording element substrate is exposed;joining the electrode pad disposed along a side of the recording elementsubstrate to the electrode lead wire extending from an edge of theopening of the electric wiring member; bending a protrusion formed inthe opening and extending between a side surface of the recordingelement substrate and an inner side surface of the recess facing theside surface so a distal end of the protrusion contacts the bottomsurface of the protrusion; and applying a sealant into a regionsurrounded by a surface of the protrusion, the bottom surface of therecess, the inner side surface of the recess, and the side surface ofthe recording element substrate so a joint between the electrode pad andthe electrode lead wire is covered by the sealant.

Further features will become apparent from the following description ofexemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a liquid discharge head cartridgeaccording to a first embodiment, and FIG. 1B is an exploded perspectiveview of the liquid discharge head.

FIG. 2A is a plan view of the front side of a recording elementsubstrate according to the first embodiment, and FIG. 2B is a plan viewof the back side of the recording element substrate.

FIG. 3A is a schematic enlarged view of the recording element substrateaccording to the first embodiment and the vicinity thereof, FIG. 3B is asectional view taken along line IIIB-IIIB of FIG. 3A, and FIG. 3C is asectional view taken along line IIIC-IIIC of FIG. 3A.

FIGS. 4A and 4B are schematic views of an electric wiring memberaccording to the first embodiment.

FIGS. 5A to 5C are schematic sectional views of a protrusion of theelectric wiring member according to the first embodiment and thevicinity thereof.

FIGS. 6A and 6B are schematic views of the protrusion of the electricwiring member according to the first embodiment.

FIG. 7A is a schematic enlarged view of a recording element substrateaccording to a second embodiment and the vicinity thereof, FIG. 7B is asectional view taken along line VIIB-VIIB of FIG. 7A, and FIG. 7Cillustrates a modification of the second embodiment.

FIG. 8A is a schematic sectional view of a protrusion of a recordingelement substrate according to a third embodiment and the vicinitythereof, FIG. 8B is a schematic sectional view of a modification of theprotrusion, and FIG. 8C is a schematic view of the protrusion.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described withreference to the drawings. Here, an ink tank and a liquid discharge headare integrated with each other. However, the ink tank may be detachablefrom the liquid discharge head.

FIG. 1A is a perspective view of a liquid discharge head cartridge 100as disclosed herein. FIG. 1B is an exploded perspective view of a liquiddischarge head portion of the liquid discharge head cartridge 100. Inthe following description, the liquid discharge head cartridge may bereferred to as a “head cartridge”.

FIG. 2A is a plan view of the front side of a recording elementsubstrate 101 of the liquid discharge head portion, and FIG. 2B is aplan view of the back side of the recording element substrate 101.

As illustrated in FIGS. 2A and 2B, the recording element substrate 101is a substantially rectangular plate-shaped member made from a silicon(Si) material and having a thickness of 0.625 mm. Electrothermaltransducers (not shown) are arranged on the front side of the recordingelement substrate 101. The electrothermal transducers generate energyfor discharging ink. Electrode pads 204 are arranged on the front sideof the recording element substrate 101 along at least one of the sides(in the first embodiment, along two opposite short sides) of therecording element substrate 101. Wiring lines (not shown) made fromaluminium (Al) are disposed on the front side of the recording elementsubstrate 101. The wiring lines electrically connect the electrode pads204 to the electrothermal transducers so that electric power is suppliedto the electrothermal transducers. The electrothermal transducers, theelectrode pads 204, and the wiring lines are formed by film deposition.In the first embodiment, heaters are used as the electrothermaltransducers.

A flow passage forming member 202 is formed on the front side of therecording element substrate 101 by photolithography. Ink discharge ports201 and ink flow passages (not shown) are formed in the flow passageforming member 202 so as to correspond to the electrothermaltransducers. A common liquid supply port 203 for supplying ink to theink flow passages is formed in the recording element substrate 101. Theliquid supply port 203 extends through the recording element substrate101 and has an opening extending in the longitudinal direction of therecording element substrate 101.

An electric wiring member 102 includes an opening 104 (device hole),which has a substantially rectangular shape, and electrode lead wires105. The recording element substrate 101 is disposed in the opening 104.The electrode lead wires 105 are connected to the electrode pads 204,which are disposed on the recording element substrate 101. The electrodelead wires 105 extend toward the inside of the opening 104 from sides(edges) of the opening 104. To be specific, the electrode lead wires 105extend toward the inside of the opening 104 from two shorts sides of theopening 104 facing two short sides of the recording element substrate101 along which the electrode pads 204 are arranged.

The electric wiring member 102 further includes external signal inputterminals 106, to which a drive control signal is input from therecording apparatus body (not shown). The external signal inputterminals 106 and the electrode lead wires 105 are connected to eachother through copper foil conductors in the electric wiring member 102,which has flexibility. The electric wiring member 102 is, for example, atape automated bonding (TAB) tape.

Each of the electrode lead wires 105 of the electric wiring member 102is joined to a corresponding one of the electrode pads 204 of therecording element substrate 101. Joints between the electrode lead wires105 and the electrode pads 204 are covered with a sealant 130, whichprotects the joints from an external force and a liquid such as ink.

A support member 103 is a part of a housing portion of the liquiddischarge head and is made by molding a resin material. In the firstembodiment, the resin material is modified polyphenylene ether. A glassfiller in the amount of 35 mass % is added to the resin material toincrease the rigidity of the support member 103. An ink supply channel107, through which ink is supplied from an ink storage portion, isformed in the support member 103. The recording element substrate 101 isbonded to the support member 103 using a thermosetting adhesive. Whenbonding the recording element substrate 101 to the support member 103,for example, the thermosetting adhesive is applied to a predeterminedposition on the support member 103, and then the recording elementsubstrate 101 is placed on the support member 103 at the predeterminedposition. The electric wiring member 102 is also fixed to the supportmember 103 using an adhesive. The recording element substrate 101 isexposed through the opening 104 of the electric wiring member 102.

FIG. 3A is a schematic enlarged view of the recording element substrate101 illustrated in FIG. 1A and the vicinity thereof. FIG. 3B is asectional view taken along line IIIB-IIIB of FIG. 3A, and FIG. 3C is asectional view taken along line IIIC-IIIC of FIG. 3A. As illustrated inFIGS. 3A to 3C, the recording element substrate 101 is disposed on thebottom surface of a recess 120 of the support member 103. To bespecific, the recess 120 for placing the recording element substrate 101therein is formed in a surface 109 of the support member 103, and therecording element substrate 101 is disposed on a bottom surface 108 ofthe recess 120. The electric wiring member 102 is bonded to a part ofthe surface 109 that surrounds the recess 120 using an adhesive. Therecording element substrate 101, which is disposed in the recess 120, isexposed through the opening 104 of the electric wiring member 102. Thereason for disposing the recording element substrate 101 on the bottomsurface 108 of the recess 120 is as follows: because the bottom surface108 is recessed from the surface 109 to which the electric wiring member102 is bonded, the height of the electrode lead wires 105 becomes thesame as that of the electrode pads 204 when the recording elementsubstrate 101, and thereby the electrode lead wires 105 can beelectrically connected to the electrode pads 204 with increasedreliability. As is clear from FIGS. 3A to 3C, the inner surface of therecess 120 includes the bottom surface 108 and inner side surfaces 110that extend substantially vertically from the sides of the bottomsurface 108.

As illustrated in FIG. 3A, four protrusions 302 are formed at fourcorners of the opening 104 of the electric wiring member 102. In otherwords, the protrusions 302 extend from the sides (edges) of the opening104 from which the electrode lead wires 105 extend. To be specific, twoof the protrusions 302 extend from one of the short sides of the opening104 toward the inside of the opening 104, and the other two protrusions302 extend from the other short side of the opening 104 toward theinside of the opening 104. Each of the protrusions 302 extends in a gapbetween a side (long side) of the recording element substrate 101 alongwhich the electrode pads 204 are not arranged and one of the inner sidesurfaces 110 of the recess 120 facing the long side. In other words,each of the protrusions 302 extends in a gap between a long side surfaceof the recording element substrate 101 and the inner side surface 110 ofthe recess 120 facing the long side surface.

As illustrated in FIG. 3B, each of the protrusions 302 includes a flatportion 302 a and a bent portion 302 b. The flat portion 302 a extendsalong the plane of the opening 104. The bent portion 302 b extends froman end of the flat portion 302 a toward the bottom surface 108 of therecess 120 of the support member 103. The distal end of the protrusion302 (the distal end of the bent portion 302 b) is in contact with thebottom surface 108 of the recess 120.

As illustrated in FIGS. 3B and 3C, a space is surrounded by the backsurface of the electric wiring member 102 including the back surface ofthe protrusion 302, a side surface of the recording element substrate101, and an inner surface of the recess 120 of the support member 103;and the space is filled with the sealant 130, which is an example of afirst sealant. The sealant 130 covers the front and back sides of theelectrode lead wires 105, the electrode pads 204, and the jointstherebetween, i.e., the electrical connection portion. As is clear fromFIGS. 3B and 3C, the inner surface of the recess 120 that defines theaforementioned space includes part of the bottom surface 108 of therecess 120 and part of the inner side surfaces 110 of the recess 120.The protrusions 302 need not extend from the short sides of the opening104. Instead, the protrusion 302 may extend from the long sides of theopening 104 or from a short side and a long side of the opening 104, aslong as the protrusions 302 extend in the gaps between the side surfaceof the recording element substrate 101 and the inner side surface 110 ofthe recess 120 facing the side surface of the recording elementsubstrate 101.

Next, a step of filling the space with the sealant 130, which isincluded in a method according to the present invention, will bedescribed. First, the electrode lead wires 105 of the electric wiringmember 102 are joined to the electrode pads 204 of the recording elementsubstrate 101 by wire bonding. Subsequently, the recording elementsubstrate 101 is aligned with the bottom surface 108 of the recess 120of the support member 103, and the recording element substrate 101 isbonded to the bottom surface 108 of the recess 120 using an adhesive.Subsequently, the electric wiring member 102 is bonded to the surface109 and to a side surface of the support member 103 adjacent to thesurface 109 using an adhesive. A step of bending the electric wiringmember 102 to form the bent portion 302 b of the protrusion 302 may beperformed before joining the recording element substrate 101 to thesupport member 103, simultaneously with joining the recording elementsubstrate 101 to the support member 103, or after joining the recordingelement substrate 101 to the support member 103.

In any case, after joining the recording element substrate 101 and theelectric wiring member 102 to the support member 103, the aforementionedspace in the recess 120 is filled with the sealant 130 so as to coverthe electrical connection portion. To be specific, the sealant 130 ispoured through gaps between the electrode lead wires 105 into the spacein the recess 120 of the support member 103, and the sealant 130 issupplied until the electrical connection portion is covered by thesealant 130 (see FIG. 3C). Therefore, a sealant having an appropriateviscosity is used as the sealant 130 so that the sealant can flow intothe recess 120 of the support member 103 through the gaps between theelectrode lead wires 105.

Subsequently, the sealant 130 is cured. To reinforce the joints betweenthe electrode lead wires 105 and the electrode pads 204, a secondsealant having a higher viscosity may be applied over a part of thesealant 130 covering the joints. Alternatively, a sealant the same asthe sealant 130 may be applied over the part as a second sealant.

FIG. 4A is a schematic view of the protrusion 302 before the bentportion 302 b is formed, and FIG. 4B is a schematic view of theprotrusion 302 after the bent portion 302 b has been formed. Asillustrated in FIG. 5A, the protrusion 302 is bent such that a distalend portion thereof is in contact with the bottom surface 108 of therecess 120 of the support member 103. In this case, a relationship L1≧L2exists, where L1 is the distance (length) from the position at which theprotrusion 302 is bent (the boundary between the flat portion 302 a andthe bent portion 302 b) to the distal end of the protrusion 302 (bentportion 302 b), and L2 is the depth of the recess 120 of the supportmember 103. When this relationship exists, the gap between the distalend of the protrusion 302 and the bottom surface 108 of the recess 120is very small, and thereby the sealant 130 is prevented from leakingthrough the gap to an area around the recording element substrate 101.In contrast, if a relationship L1<L2 exists as illustrated in FIG. 5B,there is a large gap between the distal end of the protrusion 302 andthe bottom surface 108 of the recess 120, and the sealant 130 leaksthrough the gap.

As illustrated in FIG. 5C, L3 denotes the distance from one of the innerside surfaces 110 of the recess 120 facing a side surface (an endsurface in the longitudinal direction) of the recording elementsubstrate 101 to a contact point between the distal end of theprotrusion 302, which extends above the inner side surface 110 and thebottom surface 108 of the recess 120. L4 denotes the distance from theinner side surface 110 of the recess 120 to an edge of the liquid supplyport 203 that is closest to the inner side surface 110. Here, thedistance L3 and the distance L4 are linear distances along the bottomsurface 108 of the recess 120. The shape and the size of the protrusion302 are determined so that a relationship L3≦L4 exists. There are tworeasons for this. The first reason is to prevent an unwanted externalforce, which is generated by expansion and contraction of the sealant130, from acting on the recording element substrate 101. That is, aportion of the recording element substrate 101 in which the liquidsupply port 203 is formed has a mechanical strength smaller than that ofthe other portions. Therefore, if the length L4 in FIG. 5C extendsbeyond an edge of the liquid supply port 203 of the recording elementsubstrate 101, an unwanted external force generated by expansion andcontraction of the sealant 130 may act on the recording elementsubstrate 101. In this case, the probability of occurrence of inkdischarge failure or mechanical breakage due to deformation of therecording element substrate 101 is as high as that of the case where thesealant is applied to the entire periphery of the recording elementsubstrate 101. That is, the first reason is to reduce the influence ofthe unwanted external force. The second reason is to reduce the amountof the sealant used.

In addition, when the protrusion 302 has a shape illustrated in FIG. 6A,the sealant can be more reliably prevented from leaking. The protrusion302 illustrated in FIG. 6A has a shape such that the width W1 of thebent portion 302 b is slightly larger than the width W2 of a gap (FIG.6B) between the side surface in the width direction (along a long side)of the recording element substrate 101 and the inner side surface (notshown) of the recess 120 facing the side surface. Therefore, asillustrated in FIG. 6B, a part of the bent portion 302 b is brought intoclose contact with the side surface of the recording element substrate101 in the width direction, and thereby leakage of the sealant is morereliably prevented.

The recording element substrate 101 and the electric wiring member 102are joined to each other with reference to the positions of theelectrode pads 204 and the electrode lead wires 105, and there are someallowances for these positions. However, even if there are allowances,the bent portion 302 b can be reliably brought into contact with theside surface of the recording element substrate 101 in the widthdirection because the width W1 of the bent portion 302 b is increased asdescribed above, and thereby leakage of the sealant is more reliablyprevented.

Second Embodiment

Referring to FIGS. 7A to 7C, a second embodiment will be described. FIG.7A is a schematic enlarged view of a recording element substrate of aliquid discharge head according to the second embodiment and thevicinity thereof. FIG. 7B is a sectional view taken along line VIIB-VIIBof FIG. 7A.

Four projections 701 are formed on the bottom surface 108 of the recess120 of the support member 103 around the recording element substrate101. Two of the grooves 701 are illustrated in FIG. 7A. To be specific,the projections 701 are disposed between side surfaces of the recordingelement substrate 101 in the width direction and the inner side surfaceof the recess 120 of the support member 103 facing the side surfaces.The distal end (of the bent portion 302 b) of each of the protrusions302 of the electric wiring member 102 abuts against and is engaged witha corresponding one of the projections 701. Therefore, even if theelasticity of the protrusions 302 is comparatively low, the sealant 130can be reliably prevented from leaking from the back sides of theprotrusions 302.

Because the projections 701 are formed simultaneously with molding thesupport member 103, the number of the components and the number ofproduction steps do not increase. The shape of the projections 701 maybe a rectangular parallelepiped as illustrated in FIGS. 7A to 7C, or maybe any appropriate shape. The size of the projections 701 is notparticularly limited as long as the width is smaller than the width W2shown in FIG. 6B and the height is smaller than that of the recordingelement substrate 101.

The protrusions 302 need not be completely bent. Instead, as illustratedin FIG. 7C, the protrusions 302 may maintain its shape when the distalends thereof are made to abut against the projections 701. In this case,a step of forming the bent portion 302 b in the protrusion 302 may beomitted. A step of curving the protrusion 302 as illustrated in FIG. 7Bmay be performed simultaneously with a step of joining the recordingelement substrate 101 to the bottom surface 108 of the recess 120 of thesupport member 103 by using a jig.

Third Embodiment

Referring to FIGS. 8A to 8C, a third embodiment will be described. FIG.8A is a schematic sectional view of a protrusion of a recording elementsubstrate according to the third embodiment and the vicinity thereof.

Four grooves 801 are formed in the bottom surface 108 of the recess 120of the support member 103 around the recording element substrate 101.One of the grooves 801 is illustrated in FIG. 8A. To be specific, thegrooves 801 are disposed between side surfaces of the recording elementsubstrate 101 in the width direction and inner side surfaces of therecess 120 of the support member 103 facing the side surfaces. Thedistal end of each of the protrusions 302 of the electric wiring member102 is fitted into and engaged with a corresponding one of the grooves801. Therefore, even if the elasticity of the protrusions 302 iscomparatively low, the sealant 130 can be reliably prevented fromleaking from the back sides of the protrusions 302. Because the grooves801 are formed simultaneously with molding the support member 103, thenumber of the components and the number of production steps do notincrease.

In the third embodiment, a tab portion 802 is formed at the distal endof the protrusion 302 as illustrated in FIG. 8C so that the distal endof the protrusion 302 can be reliably inserted into the groove 801. Theshape of the grooves 801 is not limited to the shape illustrated inFIGS. 8A and 8B and may be any appropriate shape. The size of thegrooves 801 is not particularly limited as long as its width is smallerthan the width W2 in FIG. 6B.

Also in the third embodiment, the width W1 of the protrusion 302 may beslightly larger than the width W2 in FIG. 6B.

The protrusions 302 need not be completely bent. Instead, as illustratedin FIG. 8B, the protrusions 302 may be configured to maintain its shapewhen the distal ends thereof are fit into the grooves 801. In this case,a step of forming the bent portion 302 b in the protrusion 302 may beomitted. The step of curving the protrusion 302 as illustrated in FIG.8B may be performed simultaneously with a step of joining the recordingelement substrate 101 to the support member 103 by using a jig.

A liquid discharge head according to the invention can be used in ageneral printer, a copier, a facsimile having a communication unit, aword processor having a printer, or a multifunction device having thefunctions of these devices.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2011-148187 filed Jul. 4, 2011, which is hereby incorporated byreference herein in its entirety.

1. A liquid discharge head comprising: a recording element substrateincluding an electrode pad for sending a signal to an element thatgenerates energy used to discharge liquid; a support member including arecess that supports the recording element substrate on a bottom surfacethereof; an electric wiring member joined to a surface of the supportmember in which the recess is formed, the electric wiring memberincluding an opening through which the recording element substrate isexposed, an electric lead wire extending from the opening and connectedto the electrode pad, and a protrusion formed in the opening andextending between a side surface of the recording element substrate andan inner side surface of the recess facing the side surface, a distalend of the protrusion contacting the bottom surface of the recess; and asealant disposed in a region surrounded by a surface of the protrusion,the bottom surface of the recess, the inner side surface of the recess,and the side surface of the recording element substrate.
 2. The liquiddischarge head according to claim 1, wherein a projection is formed onthe bottom surface of the recess and the distal end of the protrusionengaging the projection.
 3. The liquid discharge head according to claim1, wherein a groove is formed in the bottom surface of the recess andthe distal end of the protrusion engaging the groove.
 4. The liquiddischarge head according to claim 1, wherein the protrusion includes aflat portion extending along a plane of the opening and a bent portionbent to extend from the flat portion toward the bottom surface of therecess.
 5. The liquid discharge head according to claim 4, wherein arelationship L1≧L2 exists, where L1 is a length from a boundary betweenthe flat portion and the bent portion to the distal end of theprotrusion and L2 is a depth of the recess.
 6. The liquid discharge headaccording to claim 1, wherein a part of the protrusion contacts the sidesurface of the recording element substrate.
 7. The liquid discharge headaccording to claim 1, wherein a part of the protrusion contacts theinner side surface of the recess.
 8. The liquid discharge head accordingto claim 1, wherein a second sealant is superposed on the sealant. 9.The liquid discharge head according to claim 8, wherein the sealant andthe second sealant are the same sealant.
 10. The liquid discharge headaccording to claim 8, wherein a viscosity of the second sealant isgreater than a viscosity of the sealant.
 11. The liquid discharge headaccording to claim 1, wherein a liquid supply port extends through therecording element substrate, and wherein a relationship L4≧L3 exists,where L3 is a distance extending along the bottom surface of the recessfrom an inner side surface of the recess facing a side surface of therecording element substrate along which the electrode pad is formed tothe distal end of the protrusion, and L4 is a distance extending alongthe bottom surface of the recess from the inner side surface of therecess facing the side surface of the recording element substrate alongwhich the electrode pad is formed to an edge of the liquid supply portclosest to the inner side surface.
 12. A method of making a liquiddischarge head comprising: preparing a recording element substrate, asupport member, and an electric wiring member, the recording elementsubstrate including an electrode pad for sending a signal to an elementthat generates energy used to discharge liquid, the support memberincluding a recess for supporting the recording element substrate on abottom surface thereof, the electric wiring member including an electriclead wire to be connected to the electrode pad and an opening throughwhich the recording element substrate is exposed; joining the electrodepad disposed along a side of the recording element substrate to theelectrode lead wire extending from an edge of the opening of theelectric wiring member; bending a protrusion formed in the opening andextending between a side surface of the recording element substrate andan inner side surface of the recess facing the side surface so a distalend of the protrusion contacts the bottom surface of the protrusion; andapplying a sealant into a region surrounded by a surface of theprotrusion, the bottom surface of the recess, the inner side surface ofthe recess, and the side surface of the recording element substrate so ajoint between the electrode pad and the electrode lead wire is coveredby the sealant.
 13. The method of making a liquid discharge headaccording to claim 12, further comprising: applying a second sealantover the sealant after the region has been filled with the sealant. 14.The method of making a liquid discharge head according to claim 12,wherein bending of the protrusion is performed so a flat portion and abent portion are formed in the protrusion, the flat portion extendingalong a plane of the opening and the bent portion extending from an endof the flat portion toward the bottom surface of the recess.
 15. Themethod of making a liquid discharge head according to claim 12, whereinbending of the protrusion is performed so that a relationship L1≧L2exists, where L1 is a length from a boundary between the flat portionand the bent portion to the distal end of the protrusion and L2 is adepth of the recess.